Study On Hot Rolling Stability And Oxide Scale Of Nb-Ti Micro-alloyed Steel

There is an increasing demand for lightweight of automotive.The steel is still the main material for automotive manufacture,but the conventional mild steels have been replaced by high strength steels.The micro-alloyed steel whose strength and toughness can be achieved by additions of Nb,Ti and V is the main development trend of high strength steel.In the present work,the production stability and the control of surface quality of Nb-Ti micro-alloyed steel during hot rolling at 1780mm hot strip plant in Baosteel were investigated.The 1780mm hot strip plant is a short process line designed for stainless steels.The mode to calculate FET temperature and the control in gap were investigated and analyzed to promote the judgment ability of model for abnormal situation.According to short process for manufacture on stainless steel,the method on improving the accuracy of FET calculating and gap controlling was researched in 1780mm hot strip plant.With enhancing the the ability of model to judge the abnormal situation,It was proved that limiting action and the amount of roll and side guides can reduce the deviation accident.An appropriate increase in bending force and the heating temperature on the tail of the slab,at the same time,adjusting the angle of PC in F3-F4 within the range of 0.4°-0.6°,can improve stability.In terms of improving iron oxide,temperature control,roller surface protection work as well as the related equipment improvement were researched.It was proved that reducing FET,distributing load and optimizating rolling plan can reduce the incidence of defects in the oxide scale.The scrap accident and oxide scale defects of automotive steel have been effectively lowered by improving process of QSTE steel and device control,and the productivity has been greatly enhanced.